Method for adjusting a continuous casting installation roll segment

ABSTRACT

The present invention relates to an adjusting method for a roller section of a continuous casting machine which is provided with a section input side ( 6 ), a section output side ( 7 ) and a pair of roller carriers ( 1, 2 ) which each carry at least two rollers ( 3 ) extending over a supporting zone ( 4 ), with the roller carriers ( 1, 2 ) being mutually adjusted against one another by way of an adjusting unit arranged at the section input side ( 6 ) and at the section output side ( 7 ), with each adjusting unit being provided with two hydraulic cylinder units ( 8  to  11 ) arranged on either side of the supporting zone ( 4 ), characterized in that 
     the hydraulic cylinder units ( 8  to  11 ) can be adjusted both in a position-controlled and pressure-controlled manner; 
     the rollers ( 3 ) are placed in a position-controlled manner by the hydraulic cylinder units ( 8  to  11 ) against a metal billet ( 5 ) which is guided by the rollers ( 3 ); 
     the hydraulic cylinder units ( 8  to  11 ) are changed over from position-controlled to pressure-controlled operation when the pressure in the respective hydraulic cylinder unit ( 8  to  11 ) reaches a hydraulic cylinder threshold value.

The present invention relates to an adjusting method for a rollersection of a continuous casting machine which is provided with a sectioninput side and a section output side and a pair of roller carriers whicheach carry at least two rollers extending over a supporting zone, withthe roller carriers being mutually adjustable towards one another bymeans of an adjusting unit arranged at the section input side andsection output side, with each adjusting unit being provided withhydraulic cylinder units on either side of the supporting zone.

Such an adjusting method is known from DE 196 27 336 C1 for example.

During the continuous casting of metal for example, and during thecasting of a steel strip in particular, the solidifying billet is drawnoff and supported via a roller course with a plurality of supportingrollers. In order to ensure the precisest possible guidance of thebillet, the roller course is broken down into several sections accordingto DE 196 27 336 C1 which can be adjusted separately.

Bellying can occur in the still cast-heated metal billets, whichmoreover are not yet solidified in the core region. When such a bellyingpasses through a roller section, an even larger force than usual isexerted on the section. This may under certain circumstances lead todamage to the roller section. Moreover, the bellying must be compensatedagain during the further processing of the metal billet.

It is the object of the present invention to provide an adjusting methodby means of which damage to the roller section as a result of excessiveexertion of force can be avoided in any case and, moreover, bellying canbe eliminated to the highest possible extent.

This object is achieved in such a way that the hydraulic cylinder unitsare adjustable both in a position-controlled as well pressure-controlledmanner, that the rollers are moved via the hydraulic cylinder units in aposition-controlled manner towards a metal billet which is supported bythe same and that the hydraulic cylinder units can be changed over fromposition-controlled to pressure-controlled operation when the pressurein the respective hydraulic cylinder unit reaches a hydraulic cylinderthreshold value.

Preferably, a hydraulic cylinder unit will also be changed over from aposition-controlled to a pressure-controlled operation when the pressurein the other hydraulic cylinder unit of the same adjusting unit reachesthe hydraulic cylinder threshold value. This substantially causes asynchronism between the two hydraulic cylinder units of each adjustingunit.

Any overload of the rollers can be avoided in a simple manner when thehydraulic cylinder units of an adjusting unit are changed over from aposition-controlled to pressure-controlled operation when the sum totalof the pressures in the hydraulic cylinder units of the adjusting unitreaches an adjusting unit,threshold value.

Similarly, an overload of the roller section can be avoided when allhydraulic cylinder units of the roller section are changed over fromposition-controlled to pressure-controlled operation when the sum totalof the pressures in the hydraulic cylinder units reaches a sectionthreshold value.

In an embodiment of the present invention the adjusting unit producesafter the changeover from the positional control to pressure or forcecontrol a permanent form closure between the metal billet and therollers. As a result of this measure, bellying of the metal billet and,optionally, its break-out are avoided. The form closure between themetal billet and the rollers ensures the rotation of the rollers andthus their optimized cooling. Moreover, the form closure produces thecontinuous conveyance of the metal billet between the rollers.

The hydraulic cylinder threshold value, the adjusting unit thresholdvalue and the section threshold value are preferably parameterizable inorder to enable the adjustment to the constructional conditions of theroller section.

Further advantages and details are revealed by the description of anembodiment below. The elementary drawings show as follows:

FIG. 1 shows a roller section of a continuous casting machine and

FIG. 2 shows a control circuit for driving the roller section.

In accordance with FIG. 1, a roller section of a continuous castingmachine is provided with two roller carriers 1, 2, each with six rollers3. Rollers 3 extend over a supporting zone 4. The roller carriers 1, 2are placed with their rollers 3 in the supporting zone 4 against a metalbillet 5, which is a steel strip 5 in this case The metal billet 5enters the roller section at a section input side 6 and leaves thesection again at a section output side 7.

The roller carriers 1, 2 are mutually connected by way of two adjustingunits. The one adjusting unit is provided with two hydraulic cylinderunits 8, 9 which are arranged at either side of the supporting zone 4 atthe section input side 6. The other adjusting unit is provided with twohydraulic cylinder units 10, 11 which are arranged on either side of thesupporting zone 4 at the section output side 7. The roller carriers 1, 2are mutually adjustable by means of the adjusting units.

Each of the hydraulic cylinder units 8 to 11 can be controlled both withrespect to position and pressure. According to FIG. 2 each of thehydraulic cylinder units 8 to 11 are therefore assigned pressure sensors12, 13 and locators 14. Their output signals are transmitted to acomputer unit 15. The computer unit 15 determines the actuating signalsfor the hydraulic cylinder units 8 to 11 and sends the same to thecontrol valves 16, so that the hydraulic cylinder units 8 to 11 can bemoved for setting.

At the beginning of a casting process all hydraulic cylinder units 8 to11 are moved in such a way that the rollers 3 of the roller carriers 1,2 are placed against the metal billet 5 in a position-controlled way.The hydraulic cylinder units 8 to 11 are driven synchronously for eachadjusting unit. The settings to which the hydraulic cylinder units 8 to11 are adjusted are determined by the computer unit 15 independent fromone another. The settings are determined by the computer unit 15 andsent as predetermined values to the hydraulic cylinder units 8 to 11 insuch a way that force-induced spring-backs (e.g. of the roller carriers1, 2) are compensated. The position-controlled placement of the rollers3 on metal billet 5 is maintained until (as a result of a bellying inthe metal billet 5 for example) the pressure in one of the hydrauliccylinder units 8 to 11 (e.g. hydraulic cylinder unit 8 for example)reaches a hydraulic cylinder threshold value. When the pressure in thishydraulic cylinder unit 8 reaches a hydraulic cylinder threshold value,this hydraulic cylinder unit 8 is changed over to pressure-controlledoperation.

The hydraulic cylinder unit 8 then holds the pressure at the hydrauliccylinder threshold value and therefore yields.

In principle it is possible to control each of the hydraulic cylinderunits 8 to 11 in such a way independently from one another. Preferably,however, the hydraulic cylinder units 8 to 11 of the adjusting units arechanged over in groups. The hydraulic cylinder unit 9 is thereforechanged over from position-controlled operation to pressure-controlledoperation simultaneously with the hydraulic cylinder unit 8.

In accordance with the present invention, not only the individualpressures prevailing in the hydraulic cylinder units 8 to 11 arecompared with the hydraulic cylinder threshold value, but summary valuesare also formed and compared with further threshold values. Thus, thehydraulic cylinder units 8 and 9 are changed over for example fromposition-controlled to pressure-controlled operation when the sum totalof the pressures in the hydraulic cylinder units 8 and 9 reaches anadjusting unit threshold value. Similarly, the hydraulic cylinder units10 and 11 are changed over from position-controlled topressure-controlled operation when the sum total of the pressures in thehydraulic cylinder units 10 and 11 reaches the adjusting unit thresholdvalue. Moreover, all four hydraulic cylinder units 8 to 11 are changedover simultaneously from position-controlled to pressure-controlledoperation when the sum total of the pressures in the hydraulic cylinderunits 8 to 11 reaches a section threshold value.

The hydraulic cylinder threshold value, the adjusting unit thresholdvalue and/or the section threshold value are preferably parameterizableso as to enable the adjustability to the concrete conditions of theroller section. In particular, the threshold values can be parameterizedin such a way that overloads of the roller carriers 1, 2, the rollers 3and the roller pins (not shown) of rollers 3 and the bearings (also notshown) for the roller pins are avoided.

LIST OF REFERENCE NUMERALS

2 Roller carriers

3 Rollers

4 Supporting zone

5 Metal billet

6 Section input side

7 Section output side

8 to 11 Hydraulic cylinder units

12, 13 Pressure sensors

14 Locator

15 Computer unit

16 Control valves

What claimed is:
 1. An adjusting method for a roller section of acontinuous casting machine which is provided with a section input side(6), a section output side (7) and a pair of roller carriers (1, 2)which each carry at least two rollers (3) extending over a supportingzone (4), with the roller carriers (1, 2) being adjusted against oneanother by way of an adjusting unit arranged at the section input side(6) and at the section output side (7), with each adjusting unit beingprovided with two hydraulic cylinder units (8 to 11) arranged on eitherside of the supporting zone (4), wherein the hydraulic cylinder units (8to 11) can be adjusted both in a position-controlled andpressure-controlled manner; the rollers (3) are placed by the hydrauliccylinder units (8 to 11) in a position-controlled manner against a metalbillet (5) which is guided by the rollers (3); the hydraulic cylinderunits (8 to 11) are changed over from position-controlled topressure-controlled operation when the pressure in the respectivehydraulic cylinder unit (8 to 11) reaches a hydraulic cylinder thresholdvalue.
 2. The adjusting method as claimed in claim 1, wherein ahydraulic cylinder unit (e.g. 9) will also be changed over fromposition-controlled to pressure-controlled operation when the pressurein the other hydraulic cylinder unit (e.g. 8) of the same adjusting unitreaches the same hydraulic cylinder threshold value.
 3. The adjustingmethod as claimed in claim 1, wherein the hydraulic cylinder thresholdvalue is parameterizable.
 4. The adjusting method as claimed in claim 1,wherein the hydraulic cylinder units (8, 9; 10, 11) of an adjusting unitwill be changed over from position-controlled to pressure-controlledoperation when the sum total of the pressures in the hydraulic cylinderunits (8, 9; 10, 11) of the adjusting unit reaches an adjusting unitthreshold value.
 5. The adjusting method as claimed in claim 4, whereinthe adjusting unit threshold value is parameterizable.
 6. The adjustingmethod as claimed in claim 1, wherein all hydraulic cylinder units (8 to11) of the roller section will be changed over from position-controlledto pressure-controlled operation when the sum total of the pressures inthe hydraulic cylinder units (8 to 11) reaches a section thresholdvalue.
 7. The adjusting method as claimed in claim 6, wherein thesection threshold value is parameterizable.
 8. The adjusting method asclaimed in claim 1, wherein the hydraulic cylinder units (8, 9; 10, 11)of the adjusting units are driven synchronously in position-controlledoperation.
 9. The adjusting method as claimed in claim 1 whereinadjustments are sent as predetermined values to the hydraulic cylinderunits (8 to 11) in position-controlled operation in such a way thatforce-induced position fluctuations are compensated.
 10. The adjustingmethod as claimed in claim 1, wherein in position-controlled operationthe hydraulic cylinder units (8 to 11) are set to mutually independentlydetermined adjustments.
 11. The adjusting method as claimed in claim 1wherein the adjusting unit causes a positive engagement between themetal billet (5) and the rollers (3) after changing over from positionalcontrol to pressure/force control.